Haddon and Shackleton — Actinice : I. Zoanthece. 693 



TOREES STRAITS SPECIES OF THE GENUS PALYTHOA. 



P. howesii, n. sp. 

 P. Jcocliii, n. sp. 

 P. cobsia (?), Dana. 



Palythoa howesii, n. sp. 

 (PI. Lxi., fig. 13; PL Lxm., fig. 8.) 



Form. — Polyps scarcely projecting above the surface of the coenenchjane when 

 contracted, and then, in most cases, only the one side is prominent ; in other words 

 the side is almost invariably entirely sunk. Ccenenchyme, thick, incrusting. The 

 polyps are arranged in indefinite, roughly parallel rows. Owing to the partial 

 immersion of the polyps the prominent portions of contiguous polyps have a 

 tendency to form zigzag lines. The whole surface is very rigid and rough, 

 owing to the incrustation of sandy particles. . 



Colour. — Sandy. 



Dimensions. — Average diameter of jDolyps, 7 mm. 



Locality. — Fringing reef, Thursday Island. One colony. 



Named after Prof. G. B. Howes, of the Royal College of Science, London. 

 [I would like to take this opportunity of acknowledging the assistance which my 

 friend Professor Howes has rendered me from first to last in the storing and 

 distribution of my Torres Straits collections. — A. C. H.] 



Body-wall (PI. LXiii., fig. 8).— As in other species] of Palythoa, the body-wall 

 and coenenchyme are indistinguishable. The ectoderm which covers the surface 

 of the colony is much torn, fragments of it alone adhering to the mesoo-loea • these 

 pieces are further broken by irregular projections of the mesoglcea, which somewhat 

 resemble the mesogloeal strands found in various other species of Zoanthe^ but 

 they do not appear to unite in this case to form a peripheral layer of mesoo-loea. 

 In most cases no cuticle is to be seen, but in one or two places we have found a 

 thin cuticle, and it seems probable that in a normal condition such a cuticle covers 

 the surface of the ectoderm. The mesoglcea is very thick, and the incrustations 

 are chiefly found in the outer portion. The incrustations consist of coarse 

 grains of sand, and are very numerous. Lacunse, some of which are clearly 

 connected with the ectoderm, are scattered through the mesoglcea. In some cases 



